Could a pterodactyl as large as a light aircraft have flown? Did millipedes once grow to six feet long? How did insects become preserved in amber for over 50 million years? All these questions and more are answered through the study of fossils. In his journeys to the most famous fossil sites in the world, Sir David Attenborough discovers a pre-historic world teeming with life and full of enticing clues as to how life evolved. They reveal how dinosaurs hunted, lived in groups and cared for their young. And they offer glimpses of the most bizarre creatures that ever lived, such as tiny horses and an animal that is half bird and half reptile. With the help of expert palaeontologists, fossil enthusiasts from around the world and sophisticated modelling. Lost Worlds, Vanished Lives breathes life into Earth's distant past.

Sir David Attenborough visits several museums of natural history. With the aid of dinosaur skeletons, he demonstrates how they existed in real life, and speculates about the reasons for their sudden demise.